﻿using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows;
using System.Windows.Controls;

namespace CCF20Module
{
  public static class PasswordBoxAssistant 
  { 
      public static readonly DependencyProperty BoundPassword =   
          DependencyProperty.RegisterAttached("BoundPassword", typeof(string), typeof(PasswordBoxAssistant), new PropertyMetadata(string.Empty, OnBoundPasswordChanged)); 
      public static readonly DependencyProperty BindPassword = 
          DependencyProperty.RegisterAttached("BindPassword", typeof (bool), typeof (PasswordBoxAssistant), new PropertyMetadata(false, OnBindPasswordChanged)); 
      private static readonly DependencyProperty UpdatingPassword = 
          DependencyProperty.RegisterAttached("UpdatingPassword", typeof(bool), typeof(PasswordBoxAssistant), new PropertyMetadata(false));
      private static void OnBoundPasswordChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
      {
          PasswordBox box = d as PasswordBox;
          // only handle this event when the property is attached to a PasswordBox
          // and when the BindPassword attached property has been set to true
          if (d == null || !GetBindPassword(d))
          {
              return; 
          }
          // avoid recursive updating by ignoring the box's changed event 
          box.PasswordChanged -= HandlePasswordChanged;
          string newPassword = (string)e.NewValue;
          if (!GetUpdatingPassword(box)) 
          {
              box.Password = newPassword;     
          }
          box.PasswordChanged += HandlePasswordChanged;  
      }
      private static void OnBindPasswordChanged(DependencyObject dp, DependencyPropertyChangedEventArgs e)
      {
          // when the BindPassword attached property is set on a PasswordBox,
          // start listening to its PasswordChanged event 
          PasswordBox box = dp as PasswordBox; 
          if (box == null)
          {
              return;
          }
          bool wasBound = (bool)(e.OldValue);
          bool needToBind = (bool)(e.NewValue);       
          if (wasBound)
          {
              box.PasswordChanged -= HandlePasswordChanged;  
          }
          if (needToBind)
          {
              box.PasswordChanged += HandlePasswordChanged;  
          }
      }
      private static void HandlePasswordChanged(object sender, RoutedEventArgs e)  
      {
          PasswordBox box = sender as PasswordBox; 
          // set a flag to indicate that we're updating the password 
          SetUpdatingPassword(box, true);
          // push the new password into the BoundPassword property
          SetBoundPassword(box, box.Password);  
          SetUpdatingPassword(box, false);    
      }
      public static void SetBindPassword(DependencyObject dp, bool value)  
      {
          dp.SetValue(BindPassword, value);  
      }
      public static bool GetBindPassword(DependencyObject dp) 
      {
          return (bool)dp.GetValue(BindPassword);  
      }      
      public static string GetBoundPassword(DependencyObject dp)  
      {
          return (string)dp.GetValue(BoundPassword);    
      }
      public static void SetBoundPassword(DependencyObject dp, string value)
      {
          dp.SetValue(BoundPassword, value);  
      }
      private static bool GetUpdatingPassword(DependencyObject dp)   
      {
          return (bool)dp.GetValue(UpdatingPassword);   
      }
      private static void SetUpdatingPassword(DependencyObject dp, bool value)  
      {
          dp.SetValue(UpdatingPassword, value);   
      }
  }
}

